<SUBMISSION>
<ACCESSION-NUMBER>0000950134-09-003831
<TYPE>DEFA14A
<PUBLIC-DOCUMENT-COUNT>1
<FILING-DATE>20090226
<DATE-OF-FILING-DATE-CHANGE>20090226
<EFFECTIVENESS-DATE>20090226
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>F5 NETWORKS INC
<CIK>0001048695
<ASSIGNED-SIC>3576
<IRS-NUMBER>911714307
<STATE-OF-INCORPORATION>WA
<FISCAL-YEAR-END>0930
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>DEFA14A
<ACT>34
<FILE-NUMBER>000-26041
<FILM-NUMBER>09636554
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>401 ELLIOT AVE WEST
<STREET2>STE 500
<CITY>SEATTLE
<STATE>WA
<ZIP>98119
<PHONE>2062725555
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>401 ELLIOT AVE WEST
<STREET2>STE 500
<CITY>SEATTLE
<STATE>WA
<ZIP>98119
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>F5 LABS INC
<DATE-CHANGED>19990305
</FORMER-COMPANY>
</FILER>
<DOCUMENT>
<TYPE>DEFA14A
<SEQUENCE>1
<FILENAME>v51655defa14a.htm
<DESCRIPTION>DEFINITIVE ADDITIONAL MATERIALS
<TEXT>
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<TITLE>defa14a</TITLE>
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<DIV style="font-family: 'Times New Roman',Times,serif">





<DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>UNITED STATES<BR>
SECURITIES AND EXCHANGE COMMISSION</B>
</DIV>

<DIV align="center" style="font-size: 12pt"><B>Washington, DC 20549</B>
</DIV>

<DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>SCHEDULE 14A</B>
</DIV>


<DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE<BR>
SECURITIES EXCHANGE ACT OF 1934</B>
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Filed by the Registrant <FONT face="Wingdings">&#254;</FONT>

</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Filed by a Party other than the Registrant <FONT face="Wingdings">&#111;</FONT>

</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Check the appropriate box:

</DIV>

<DIV style="margin-top: 6pt">
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Preliminary Proxy Statement</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD><B>Confidential, for Use of the Commission Only (as permitted by Rule&nbsp;14a-</B><B>6(e)(2)</B><B>)</B></TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Definitive Proxy Statement</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#254;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Definitive Additional Materials</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Soliciting Material under &#167; 240.14a-12</TD>
</TR>

</TABLE>
</DIV>
<DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>F5 NETWORKS, INC.</B>
</DIV>

<DIV align="center" style="font-size: 10pt"><B>(Name of Registrant as Specified in Its Charter)</B></DIV>


<DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>N/A<BR>
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)</B></DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Payment of Filing Fee (Check the appropriate box):

</DIV>

<DIV style="margin-top: 6pt">
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#254;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>No fee required.</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Fee computed on table below per Exchange Act Rules&nbsp;14a-6(i)(1) and 0-11.</TD>
</TR>

</TABLE>
</DIV>

<DIV style="margin-top: 6pt">
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(1)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Title of each class of securities to which transaction applies:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(2)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Aggregate number of securities to which transaction applies:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(3)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Per unit price or other underlying value of transaction
computed pursuant to Exchange Act Rule&nbsp;0-11 (set forth the
amount on which the filing fee is calculated and state how it
was determined):</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(4)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Proposed maximum aggregate value of transaction:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(5)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Total fee paid:</TD>
</TR>

</TABLE>
</DIV>

<DIV style="margin-top: 6pt">
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Fee paid previously with preliminary materials:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="3%" nowrap align="left"><FONT face="Wingdings">&#111;</FONT></TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Check box if any part of the fee is offset as provided by Exchange Act Rule&nbsp;0-11(a)(2) and
identify the filing for which the offsetting fee was paid previously. Identify the previous
filing by registration statement number, or the Form or Schedule and the date of its filing.</TD>
</TR>

</TABLE>
</DIV>

<DIV style="margin-top: 6pt">
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(1)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Amount Previously Paid:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(2)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Form, Schedule or Registration Statement No.:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(3)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Filing Party:</TD>
</TR>

<TR>
    <TD style="font-size: 6pt">&nbsp;</TD>
</TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="4%" style="background: transparent">&nbsp;</TD>
    <TD width="3%" nowrap align="left">(4)</TD>
    <TD width="1%">&nbsp;</TD>
    <TD>Date Filed:</TD>
</TR>

</TABLE>
</DIV>




<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
</DIV>

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<H5 align="left" style="page-break-before:always">&nbsp;</H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">







<DIV align="left" style="font-size: 10pt; margin-top: 10pt">On February&nbsp;26, 2009, F5 Networks, Inc. issued the following press release.
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>FOR IMMEDIATE RELEASE</B>
</DIV>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="10%">&nbsp;</TD>
    <TD width="3%">&nbsp;</TD>
    <TD width="87%">&nbsp;</TD>
</TR>
<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px"><B>CONTACT:</B>
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Investor Relations<br>
John Eldridge<br>
(206)&nbsp;272-6571<br>
<u>j.eldridge@f5.com </u><br></TD>
</TR>
<TR valign="bottom"><!-- Blank Space -->
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Public Relations<br>
Alane Moran<br></TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">(206) 272-6850<BR>
<u>a.moran@f5.com </u></TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>


<DIV align="center" style="font-size: 10pt; margin-top: 10pt"><B>F5 Networks Announces Proxy Advisory Firms&#146; Approval of Shareholder Proposals</B>
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">SEATTLE, WA&#151;February&nbsp;26, 2009&#151;F5 Networks, Inc. (NASDAQ: FFIV) today announced that two leading
independent proxy advisory services firms, RiskMetrics Group, Inc. and PROXY Governance, Inc. have
recommended that F5&#146;s shareholders vote &#147;FOR&#148; each of the proposals in the company&#146;s 2009 Proxy
Statement.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">Proposal 1 asks shareholders to elect one Class&nbsp;I director, Karl Guelich, unanimously nominated by
the company&#146;s Board of Directors. Proposals 2 and 3 ask shareholders to approve amendments to the
company&#146;s 2005 Equity Incentive Plan as amended and the 1999 Employee Stock Purchase Plan,
respectively. Proposal 4 asks the shareholders to ratify the selection of PricewaterhouseCoopers
LLP as the company&#146;s independent auditor for fiscal year 2009.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 6pt">As previously announced, F5&#146;s annual meeting of shareholders will be held on March&nbsp;12, 2009 at 11
a.m. Pacific time, at the company&#146;s headquarters in Seattle, Washington.
</DIV>

<DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>About F5 Networks</B>
</DIV>


<DIV align="left" style="font-size: 10pt; margin-top: 6pt">F5 Networks is the global leader in Application Delivery Networking. F5 provides solutions that
make applications secure, fast, and available for everyone. By adding intelligence and
manageability into the network to offload applications and optimize the data storage layer, F5
extends the power of intelligent networking to all levels of application delivery. F5&#146;s extensible
architecture optimizes applications, delivers application reliability, and protects the application
and network. Enterprise organizations, service providers and Web 2.0 content providers worldwide
trust F5 to keep their applications running. The company is headquartered in Seattle, Washington
with offices worldwide. For more information, go to www.f5.com.
  F5&#146;s Proxy Statement and 2008 Annual Report to Shareholders are available online at
www.proxyvote.com and www.f5.com/about/investor-relations/corporate-governance.
</DIV>


<P align="center" style="font-size: 10pt"><!-- Folio -->&nbsp;<!-- /Folio -->
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